Implementing Params for Your Structs

Implementing Params directly on a struct avoids building a HashMap or a JSON value for each render: string fields are borrowed, and only formatted values allocate.

1. Implementation

use std::borrow::Cow;
use anza::Params;

pub struct Article {
  pub id: i64,
  pub slug: String,
  pub title: String,
  pub author: String,
}

impl Params for Article {
  fn resolve(&self, key: &str) -> Option<Cow<'_, str>> {
    match key {
      "id" => Some(Cow::Owned(self.id.to_string())),
      "slug" => Some(Cow::Borrowed(self.slug.as_str())),
      "title" => Some(Cow::Borrowed(self.title.as_str())),
      "author" => Some(Cow::Borrowed(self.author.as_str())),
      _ => None,
    }
  }
}

2. Usage

let article = Article {
  id: 42,
  slug: "stui-in-rust".into(),
  title: "Server-Templated UI in Rust".into(),
  author: "Alex Rivera".into(),
};

let html = engine.get("feed/article.html")?.bind(&article)?;

Engine::get returns an Arc<Template> (no copy of the template), and bind resolves each distinct placeholder name once and allocates the output buffer once.

3. Compared with the alternatives

No benchmark numbers are published for these; measure in your own setup.

Whichever technique you use, values are inserted without HTML escaping unless Setup::escape is on (then {{name}} is escaped and {{{name}}} is raw).